1. Field of the Invention
Aspects of the present invention relate generally to data link layer switching techniques, and more particularly to a system and method enabling application of policy on a data frame using Layer 2 data fields and simplified data structures.
2. Description of Related Art
In accordance with the Open Systems Interconnection (OSI) model, a data link layer, or “Layer 2”, of a protocol stack generally facilitates data transfer between physical nodes in a data network. Layer 2 may function in conjunction with various protocols such as Ethernet (the Institute of Electrical and Electronics Engineers (IEEE) 802 standard), for instance; other protocols include high-level data link control (HDLC) and advanced data communication control protocol (ADCCP).
As is generally known in conventional switching methodologies, address databases are constructed to facilitate proper routing of data frames ingressing or egressing a port at a switch. With respect to Layer 2, various data fields associated with a particular data frame are employed to ensure proper communication of the data. These data fields generally include the following: a destination address (DA) for the frame; a source address (SA) of the frame; an EtherType, sometimes referred to as a length type, characterizing the frame; and a virtual local area network (VLAN) identification (or VID). These data fields allow Layer 2 to interface the physical layer (Layer 1) and the network layer (Layer 3) to provide appropriate data transfer of properly tagged frames.
Conventional systems are deficient, however, to the extent that Layer 2 data fields are not currently used to implement policy using a simple data structure and economical switching hardware. In particular, policy functionality has traditionally failed efficiently to take advantage of the architecture (e.g., port registers and databases) that exists to support Layer 2 switching; this is true even though some policy determinations require examination of the same data fields (and cross-reference values in those data fields against the same address databases) employed by Layer 2. Accordingly, current policy strategies are characterized by very large memory requirements, and generally employ ternary content-addressable memory (TCAM) or other high-capacity data storage components. While potentially allowing sophisticated policy features, conventional solutions add complexity and cost to switching hardware.
Hence, it would be desirable to provide a method and system that decrease the memory requirements typically associated with enabling policy features while still providing flexible switching functionality.